1. Field of Invention
The present invention relates to a structure of an illumination apparatus. More particularly, the present invention relates to a structure of an illumination apparatus for generating uniform planar light, increasing brightness and increasing illumination efficiency of a liquid crystal display.
2. Description of Related Art
Liquid crystal display (LCD) has so many advantages, including high picture quality, small volume, light weight, low driving voltage and low power consumption, that LCDs are widely applied in electronic products such as medium or small-sized portable televisions, mobile phones, videos, notebooks, and monitors for desktop computers and projection-type televisions. Therefore, as time goes by, LCDs are gradually replacing cathode ray tube (CRT) monitors.
The present LCDs are not applied only in medium-sized or small-sized panel LCD products, such as small-sized portable televisions, mobile phones, videos, notebooks and monitors for desktop computers, but also large-sized panel LCD products, such as LCD televisions. However, large-sized panel products face the problems of how to generate uniform planar light projected  onto the liquid crystal display panel, how to provide enough brightness and how to increase illumination efficiency of a LCD.
Reference is made to FIG. 1A, which is a schematic view showing a structure of a conventional light guiding system 1. Conventionally, the light sources 12 are located at two ends of the light guide rod 11. The light emitted from the light sources 12 is guided through the vertical notches 111 and then to the light guide plate 13. Finally, the light is guided through the notches 131 of the light guide plate 13 and a planar light can be projected from the light guide plate 13 onto the liquid crystal display panel (not shown). However, existence of the vertical notches 111 of the light guide rod 11 makes the generated planar light projected from the light guide plate 13 onto the liquid crystal display panel a rippled planar light rather than a uniform planar light. Hence, a diffusion plate 14 is further required to disperse the light first. On the other hand, the light sources can be only configured at two ends of the light guide rod 11. In this design, extraordinary light sources cannot be added so that the design cannot be applied in the large-sized panel LCD products which require high brightness.
Reference is made to FIG. 2, which is a schematic view showing a structure of a conventional illumination apparatus 2. The tilt planes 211 and the vertical notches 212 are formed in the light guide rod 21. The light sources 22 are located below the tilt planes 211. The light emitted from the light sources 22 is guided through the tilt planes 211 and the vertical notches 212 and to the light guide plate (not shown). Certainly, a planar light can also be generated from the light guide plate and projected onto the liquid crystal display panel (not shown). However, existence of the tilt planes 211 and the vertical  notches 212 also makes the generated planar light projected from the light guide plate onto the liquid crystal display panel a rippled planar light rather than a uniform planar light. A diffusion plate is also required to disperse the light. Although this kind of design can increase the number of the located light sources, existence of the tilt planes 211 still limits the number of the light sources 22. This structure also cannot be applied in the large-sized panel LCD products. Besides, the light emitted from the light sources 22 must be reflected from the tilt planes 211 to the vertical notches 212 first, and then guided to the light guide plate. The indirect guiding mechanism makes the illumination efficiency lower.
On the other hand, although plural light guide rods and the light sources can be also added to meet the requirement of brightness, the volume of the LCD will consequently increase. Accordingly, there is a need for the conventional a structure of an illumination apparatus to be improved.